1. Field
The subject matter disclosed herein relates to using a touch interface and more particularly relates to managing multiple touch sources with palm rejection.
2. Description of the Related Art
In general, computing device may be configured with a touch based input capability. A computing device with a touch based interface, or input system, may allow a user to communicate with the computing device. Through a touch interface, a user may change settings, execute programs, respond to notifications, or operate the computing device in another way. As the accuracy and sensitivity of touch based technologies increases, more computing devices may offer a touch based interface.
Some computing devices incorporate multiple touch interfaces. For example, a computing device may include a handheld instrument, such as a magnetic resonance pen, with a capacitive touch interface at the touch screen. When a user is using the handheld instrument for the magnetic resonance touch interface, a user may touch the screen with a wrist or palm. This touch may activate other features or cause the computing device to behave unexpectedly. In order to address this issue, computing devices with multiple touch interfaces typically disable one or another touch interface, depending on the current activity of a user.
In one solution to palm rejection, a user touch interface is disabled while a user is using the handheld instrument, or while a touch instrument is within a certain range of the touch screen. This may reject user touches (e.g. palm rejection) while still allowing a user to communicate with the computing device using the handheld instrument. Disabling a user touch interface while a user may be using a handheld instrument does not allow a user to communicate with the device using user touch while the touch instrument is active.
In another solution to palm rejection, some systems ignore user touches that encompass a large area. A “large” area touch may frequently be associated with a size of a user's palm, wrist, forearm, or the like. Some computing devices provide palm rejection by simply ignoring such large touches. However, distinguishing between “large” touches that may not be intended touches, and other similarly sized touches that may be intended touches, may be difficult and may cause a computing device to reject touches that are intended touches by a user. For example, a large touch may begin as a small touch and grow as a user fully touches the touch screen. Also, a multi-touch action, or a gesture by a user on a touch screen may appear as a large touch. Therefore, additional methods are necessary for adequate management of multiple touch sources with palm rejection.